Refactor nautilus extension (#10106)

Following #10082 I took the opportunity to clean up the code in the
nautilus extension a little. Specifically, this pull request

- turns methods that weren't using `self` into functions,
- inlines a helper method that was trivial after #10082,
- extracts duplicate code in both menu item callbacks into a new helper
function, and
- removes the compatibility hack for the Nautilus 3.0 API, i.e. GNOME 42
and older.

I'm not that sure about the last point, as it's not clear to me what the
support baseline is here: GNOME 43 (the first version to support the
Nautilus 4.0 API) was released in Sep 2022, i.e. is almost as old as
Ghostty itself. The previous Debian stable release already included
GNOME 43, but Ubuntu 22.04 (the LTS before the current 24.04 LTS) still
includes GNOME 42. Does Ghostty support a system that old? If so, I'll
drop the corresponding commit from this PR.

dist/linux/ghostty_nautilus.py

@@ -20,50 +20,42 @@
 from gi.repository import Nautilus, GObject, Gio
 
 
-class OpenInGhosttyAction(GObject.GObject, Nautilus.MenuProvider):
-    def _open_terminal(self, path):
+def open_in_ghostty_activated(_menu, paths):
+    for path in paths:
         cmd = ['ghostty', f'--working-directory={path}', '--gtk-single-instance=false']
         Gio.Subprocess.new(cmd, Gio.SubprocessFlags.NONE)
 
-    def _menu_item_activated(self, _menu, paths):
-        for path in paths:
-            self._open_terminal(path)
 
-    def _make_item(self, name, paths):
+def get_paths_to_open(files):
+    paths = []
+    for file in files:
+        location = file.get_location() if file.is_directory() else file.get_parent_location()
+        path = location.get_path()
+        if path and path not in paths:
+            paths.append(path)
+    if 10 < len(paths):
+        # Let's not open anything if the user selected a lot of directories,
+        # to avoid accidentally spamming their desktop with dozends of
+        # new windows or tabs.  Ten is a totally arbitrary limit :)
+        return []
+    else:
+        return paths
+
+
+def get_items_for_files(name, files):
+    paths = get_paths_to_open(files)
+    if paths:
         item = Nautilus.MenuItem(name=name, label='Open in Ghostty',
             icon='com.mitchellh.ghostty')
-        item.connect('activate', self._menu_item_activated, paths)
-        return item
+        item.connect('activate', open_in_ghostty_activated, paths)
+        return [item]
+    else:
+        return []
 
-    def _paths_to_open(self, files):
-        paths = []
-        for file in files:
-            location = file.get_location() if file.is_directory() else file.get_parent_location()
-            path = location.get_path()
-            if path and path not in paths:
-                paths.append(path)
-        if 10 < len(paths):
-            # Let's not open anything if the user selected a lot of directories,
-            # to avoid accidentally spamming their desktop with dozends of
-            # new windows or tabs.  Ten is a totally arbitrary limit :)
-            return []
-        else:
-            return paths
 
-    def get_file_items(self, *args):
-        # Nautilus 3.0 API passes args (window, files), 4.0 API just passes files
-        files = args[0] if len(args) == 1 else args[1]
-        paths = self._paths_to_open(files)
-        if paths:
-            return [self._make_item(name='GhosttyNautilus::open_in_ghostty', paths=paths)]
-        else:
-            return []
+class GhosttyMenuProvider(GObject.GObject, Nautilus.MenuProvider):
+    def get_file_items(self, files):
+        return get_items_for_files('GhosttyNautilus::open_in_ghostty', files)
 
-    def get_background_items(self, *args):
-        # Nautilus 3.0 API passes args (window, file), 4.0 API just passes file
-        file = args[0] if len(args) == 1 else args[1]
-        paths = self._paths_to_open([file])
-        if paths:
-            return [self._make_item(name='GhosttyNautilus::open_folder_in_ghostty', paths=paths)]
-        else:
-            return []
+    def get_background_items(self, file):
+        return get_items_for_files('GhosttyNautilus::open_folder_in_ghostty', [file])